Tube heat exchanger having spacers

ABSTRACT

The present invention relates to a heat exchanger (1) comprising a bundle of tubes (2) arranged parallel to one another and inside of which a first heat transfer fluid is intended to circulate, a second fluid being intended to pass through the bundle of tubes (2) between said tubes (2), said bundle of tubes (2) comprising spacers (6) which are disposed between said tubes (2), said spacers (6) having corrugations (60) extending in the longitudinal direction of the tubes (2), said corrugations (60) having ridges (61) in contact with said tubes (2) and sidewalls (62) connecting said ridges (61), the spacers (6) comprising a first portion (6A) and a second portion (6B), the first portion (6A) being arranged upstream of the second portion (6B) in the direction of flow of the second heat transfer fluid, wherein the first portion (6A) protrudes from the front edge of the tubes (2), the ridges (61) of the first portion (6A) having a profile having a flat (64) and the ridges (61) of the second portion (6B) having a rounded profile (65) such that the corrugations (60) have a sinusoidal profile.

The present invention relates to a heat exchanger, and more particularly to a tube heat exchanger having fins in the automotive field.

Tube heat exchangers generally have a bundle of tubes disposed parallel to one another and inside which a first heat transfer fluid circulates. A second heat transfer fluid is for its part intended to traverse the bundle of tubes by passing between the tubes. In order to improve the exchange of heat between the two heat transfer fluids, fins are disposed between the tubes in the passage of the second heat transfer fluid.

However, for heat exchangers such as evaporators or evaporator/condensers, when the first refrigerant fluid circulating in the heat exchanger is cold and the second heat transfer fluid is also cold, there is a risk of frost forming on the surface of the heat exchanger. The formation of frost reduces the amount of second heat transfer fluid able to traverse the heat exchanger and thus reduces the efficiency of the latter. Such a phenomenon can in particular occur at an evaporator/condenser placed on the front face of the motor vehicle when the latter is used within a heat pump.

One known solution is to periodically circulate hot first heat transfer fluid within the tubes of the heat exchanger in order to melt any frost. However, it is possible that this solution is not suitable because it requires temporarily interrupting the mode of operation used. This then involves a reduction in passenger comfort.

One of the aims of the present invention is therefore to overcome at least some of the drawbacks of the prior art and propose an improved heat exchanger that has reduced risks of frost forming on its surface.

The present invention therefore relates to a heat exchanger having a bundle of tubes disposed parallel to one another and inside which a first heat transfer fluid is intended to circulate, a second fluid being intended to traverse the bundle of tubes between said tubes, said bundle of tubes having fins disposed between said tubes, said fins having corrugations extending in the direction of the length of the tubes, said corrugations having peaks in contact with said tubes and flanks connecting said peaks, the fins having a first portion and a second portion, the first portion being disposed upstream of the second portion in the direction in which the second heat transfer fluid passes through, the first portion projecting beyond the front edge of the tubes, the peaks of the first portion having a profile exhibiting a flat part and the peaks of the second portion having a rounded profile such that the corrugations have a sinusoidal profile.

The fact that the first portion of the fins projects beyond the front edge of the tubes and that its peaks have a flat part makes it possible to prevent the formation of frost. This is because the peaks with a flat part, in conjunction with the projection, make it possible to better discharge water condensates on the front face of the heat exchanger, that is to say that face of the heat exchanger via which the second heat transfer fluid enters. Frost is therefore less likely to form.

According to one aspect of the invention, the second portion extends over 100% to 66% of the width of the tubes.

According to another aspect of the invention, the first and second portions are made from one and the same part.

According to another aspect of the invention, the first and second portions are made from two separate parts.

According to another aspect of the invention, the pitch of the corrugations of the first portion and the pitch of the corrugations of the second portion are different.

According to another aspect of the invention, the pitch of the corrugations of the first portion is greater than the pitch of the corrugations of the second portion.

According to another aspect of the invention, the thickness of the first portion is greater than the thickness of the second portion.

According to another aspect of the invention, the first portion has, in the direction of the width of the tubes, at least two series of slots offset with respect to one another.

According to another aspect of the invention, the first portion extends along a rectilinear profile in the direction of the width of the tubes.

According to another aspect of the invention, the first portion extends along a corrugated profile in the direction of the width of the tubes.

Other features and advantages of the invention will become more clearly apparent from reading the following description, which is given by way of illustrative and non-limiting example, and the appended drawings, in which:

FIG. 1 is a schematic representation of a heat exchanger,

FIG. 2 is a partial schematic representation, in perspective, of a bundle of tubes of a heat exchanger,

FIG. 3 is a partial schematic representation, in section, of a first fin portion,

FIG. 4 is a partial schematic representation, in section, of a second fin portion,

FIG. 5 is a schematic partial representation, in perspective, of a fin according to a first embodiment,

FIG. 6 is a partial schematic representation, in perspective, of a fin according to a second embodiment,

FIG. 7 is a partial schematic representation, in perspective, of a fin according to a third embodiment,

FIG. 8 is a schematic partial representation, in perspective, of a fin according to a fourth embodiment.

In the various figures, identical elements bear the same reference numbers.

The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Individual features of different embodiments can also be combined and/or interchanged to provide other embodiments.

In the present description, some elements or parameters may be indexed, such as, for example, first element or second element and first parameter and second parameter or else first criterion and second criterion, etc. In this case, this is simple indexing for differentiating and denoting elements or parameters or criteria that are similar but not identical. This indexing does not imply that one element, parameter or criterion tales priority over another and such denotations can easily be interchanged without departing from the scope of the present description.

In the present description, “placed upstream” is understood to mean that one element is placed in front of another with respect to the circulation direction of a fluid. By contrast, “placed downstream” is understood to mean that one element is placed after another with respect to the circulation direction of the fluid.

FIG. 1 shows a heat exchanger 1, with an overall parallelepipedal shape, comprising a bundle formed by a multitude of tubes 2 inside which a first heat transfer fluid is intended to circulate, for example a refrigerant fluid circulating in a reversible cooling circuit. The tubes 2 have an oblong section, defined by a major axis and a minor axis, and are arranged parallel to one another. The tubes 2 are flat tubes, that is to say they have two large sides that have a planar surface and are parallel to the major axis and also two small sides that have a curved surface forming the edge of the tubes 2 and connecting the rims of the large sides. Fins 6 connecting the large sides of two adjacent tubes 2 are disposed between the tubes 2. These fins 6 act as a disruptor and increase the surface area over which heat is exchanged with a second heat transfer fluid intended to traverse the bundle of tubes 2 by passing between the tubes 2. This second heat transfer fluid may be a flow of air, for example.

The fins 6 are for example corrugated or crenellated strips, placed between the tubes 2 and fixed to said tubes 2. The tubes 2 and the fins 6 are generally made of metal, for example aluminum or aluminum alloy. The tubes 2 and the fins 6 forming the bundle are then generally fixed to one another by brazing. Reference is then made to a brazed bundle.

The heat exchanger 1 also has two manifolds 3 or header tanks, a manifold 3 being disposed at each end of the tubes 2. These manifolds 3 each have a header plate 4 and a cover 8 covering the header plate 4 and closing the manifold 3. These manifolds 3 make it possible to collect and/or distribute the first heat transfer fluid so that it circulates in the tubes 2.

The header plate 4 sealingly connects the manifold 3 and bundle of tubes 2. In addition, the header plate 4 may have a rectangular overall shape. The header plate 4 also has a multiplicity of orifices which have a shape corresponding to the shape of the section of the tubes 2 and are able to receive the ends of the tubes 2. The tubes 2 are sealingly fixed to the header plate 4.

Since the tubes 2, the fins 6 and the header plates 4 are brazed, the latter may be made of a metallic material, in particular aluminum or aluminum alloy. Reference is then made to a brazed heat exchanger 1.

As is shown in FIG. 2 , the fins 6 have corrugations 60 extending in the direction of the length of the tubes 2. What is meant here by length of the tubes 2 is the axis connecting the ends of the tubes 2 on which the manifolds 3 are fixed. The corrugations 60 have peaks 61 (visible in FIGS. 3 and 4 ) in contact with the tubes 2, more specifically with the planar surfaces of the tubes 2, and flanks 62 (visible in FIGS. 3 and 4 ) connecting said peaks 61. These peaks 61 and these flanks 62 are disposed perpendicularly to the axis of the length of the tubes 2.

The fins 6 have in particular a first portion 6A and a second portion 6B. The first portion 6A is disposed upstream of the second portion 6B in the direction in which the second heat transfer fluid passes through, represented by an arrow 100 in FIG. 2 . The first portion 6A projects beyond the tubes 2, more particularly beyond the front edge of the tubes 2. What is meant here by front edge of the tubes 2 is that edge of the tubes 2 that faces the flow of the second heat transfer fluid.

The second portion 6B stops at the rear edge of the tubes 2. What is meant here by rear edge of the tubes 2 is that edge of the tubes 2 that is opposite to the front edge.

As is shown in FIGS. 3 and 4 , the peaks 61 of the first portion 6A have a profile exhibiting a flat part 64 and the peaks 61 of the second portion 6B have a rounded profile 65 such that the corrugations 60 have a sinusoidal profile.

The fact that the first portion 6A of the fins 6 projects beyond the front edge of the tubes 2 and that its peaks 61 have a flat part 64 makes it possible to prevent the formation of frost. This is because the peaks 61 with a flat part 64, in conjunction with the projection, make it possible to better discharge water condensates on the front face of the heat exchanger 1, that is to say that face of the heat exchanger via which the second heat transfer fluid enters. Frost is therefore less likely to form.

The second portion 6B may in particular extend over 100% to 66% of the width of the tubes 2. What is meant here by width is the distance between the front edge and the rear edge of the tubes 2. When the second portion 6B extends over 100% of this width, the first portion 6A is limited to that part of the fin 6 that projects beyond the tubes 2.

The first portion 6A preferably has smooth flanks 62. These smooth flanks 62 likewise make it possible to properly discharge the condensates. The second portion 6B may for its part have louvers 63 on its flanks 62. What is meant here by louver 63 is a deflecting wall which is in one piece with the flank 62, is inclined with respect to said flank 62 and protrudes on either side of the flank 62. Said deflecting wall defines an opening on either side of the flank 62 such that the second heat transfer fluid can pass from one side of the flank 62 to the other.

As is shown in FIG. 5 , but likewise in FIG. 2 , the louvers 63 of one and the same flank 62 may all be oriented in one and the same direction. What is meant by this is that their openings on one and the same side of one and the same flank 62 all face in the same direction. Such a disposition makes it possible to properly swirl the second heat transfer fluid and improves the exchanges of heat.

According to a variant illustrated in FIG. 6 , one and the same flank 62 with corrugations 60 may have louvers 63 oriented in different directions. In the example illustrated in FIG. 6 , one and the same flank 62 has on one and the same side a first series of louvers 63 oriented toward the front edge of the tubes 2 and a second series of louvers 63 oriented toward the rear edge of the tubes 2.

Within one and the same corrugation 60, the louvers 63 of the two flanks 62 may have an identical orientation. It is likewise possible to envisage that the orientation of the louvers 63 is reversed from one flank 62 to the other.

According to a first embodiment, illustrated in particular in FIGS. 2, 5 and 6 , the first 6A and second 6B portions are made from two separate parts. The first 6A and second 6B portions then correspond to two corrugated strips disposed side by side in the direction of the length of the tubes 2.

The corrugations 60 having peaks 61 with flat parts 64 are more difficult to produce than the corrugations 60 having peaks 61 with a rounded profile 65 and it is more difficult to control the pitch of the corrugations 60. Thus, it is possible to limit these corrugations 60 having peaks 61 with flat parts 64 to the first portion 6A in order to limit the production costs of the heat exchanger 1.

The first 6A and second 6B portions are preferably disposed rim to rim and do not fit in one another. For this, the corrugations 60 of the first 6A and second 6B portions are preferably offset from one another. As can be seen in FIG. 5 , the pitch of the corrugations 60 of the first portion 6A and the pitch of the corrugations 60 of the second portion 6B may be different. More particularly, the pitch of the corrugations 60 of the first portion 6A may be greater than the pitch of the corrugations 60 of the second portion 6B.

The thickness e of the first portion 6A (visible in FIG. 3 ) may likewise be greater than the thickness e′ of the second portion 6B (visible in FIG. 4 ). This makes it possible likewise for the two portions not to fit in one another but this also makes it possible to better protect the heat exchanger 1 against impacts. This is because, on account of the first portion 6A projecting beyond the front edge of the tubes 2, the latter is more likely to sustain impacts from elements such as gravel, especially if it is an evaporator/condenser placed on the front face of the motor vehicle. A greater thickness e thus makes it possible to absorb these impacts more effectively and makes it possible to protect the heat exchanger 1, in particular its tubes 2.

The fact that the first 6A and second 6B portions are separate parts also makes it possible to vary their shapes in relation to one another in order to limit the risks of frost forming. Thus, as is illustrated in FIGS. 1, 5 and 6 , the first portion 6A may extend along a rectilinear profile in the direction of the width of the tubes 2. According to another example illustrated in FIG. 7 , the first portion 6A may extend along a corrugated profile in the direction of the width of the tubes 2.

It is likewise possible to envisage even more complex first portions 6A, for example as is illustrated in FIG. 8 . The first portion 6A may thus have, in the direction of the width of the tubes 2, at least two series of slots 601, 602, 603, 604 offset with respect to one another. In the example illustrated in FIG. 8 , the first portion 6A has four series series of slots 601, 602, 603, 604.

The first 6A and second 6B portions of the fins 6 can thus be made separately, for example by shaping two separate metal plates by means of rollers exhibiting different patterns in order to form separate peaks 61 between the first 6A and second 6B portions. The two portions 6A, 6B are then disposed side by side during the manufacture of the heat exchanger 1 and fixed to the tubes 2, for example by brazing.

According to a second embodiment, which is not shown, the first 6A and second 6B portions may be made from one and the same part. In this instance, the corrugations 60 of the first 6A and second 6B portions have a similar pitch and are aligned. The first portion 6A may have smooth flanks 62 or else corrugated flanks 62 provided that the corrugations 60 meet at the join with the second portion 6B.

Still according to this second embodiment, the first 6A and second 6B portions of the fins 6 may be made at the same time, for example by shaping a metal plate by means of rollers exhibiting different patterns in order to form separate peaks 61 between the first 6A and second 6B portions.

Therefore, it is clear that the heat exchanger 1, owing to the presence of two separate portions 6A, 6B of fin 6, makes it possible to reduce the risks of frost forming when said heat exchanger 1 is in use. 

1. A heat exchanger comprising: a bundle of tubes disposed parallel to one another and inside which a first heat transfer fluid is intended to circulate, a second fluid being intended to traverse the bundle of tubes between said tubes, said bundle of tubes having fins disposed between said tubes, said fins having corrugations extending in the direction of the length of the tubes, said corrugations having peaks in contact with said tubes and flanks connecting said peaks wherein the fins have a first portion and a second portion, the first portion being disposed upstream of the second portion in the direction in which the second heat transfer fluid passes through, the first portion projecting beyond the front edge of the tubes, the peaks of the first portion having a profile exhibiting a flat part and the peaks of the second portion having a rounded profile such that the corrugations have a sinusoidal profile.
 2. The heat exchanger as claimed in claim 1, wherein the second portion extends over 100% to 66% of the width of the tubes.
 3. The heat exchanger as claimed in claim 1, wherein the first and second portions are made from one and the same part.
 4. The heat exchanger as claimed in claim 1, wherein the first and second portions are made from two separate parts.
 5. The heat exchanger as claimed in claim 4, wherein the pitch of the corrugations of the first portion and the pitch of the corrugations of the second portion are different.
 6. The heat exchanger as claimed in claim 5, characterized in that the pitch of the corrugations of the first portion is greater than the pitch of the corrugations of the second portion.
 7. The heat exchanger as claimed in claim 4, characterized in that the thickness of the first portion is greater than the thickness of the second portion.
 8. The heat exchanger as claimed in claim 4, wherein the first portion has, in the direction of the width of the tubes, at least two series of slots offset with respect to one another.
 9. The heat exchanger as claimed in claim 1, wherein the first portion extends along a rectilinear profile in the direction of the width of the tubes.
 10. The heat exchanger as claimed in claim 1, wherein the first portion extends along a corrugated profile in the direction of the width of the tubes. 